The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Compressors are used in a wide variety of industrial and residential applications to circulate refrigerant within a refrigeration, heat pump, HVAC, or chiller system (generically referred to as “refrigeration systems”) to provide a desired heating and/or cooling effect. In any of the foregoing systems, the compressor should provide consistent and efficient operation to ensure that the particular refrigeration system functions properly.
Refrigeration systems and associated compressors may include a protection system that selectively restricts power to the compressor to prevent operation of the compressor and associated components of the refrigeration system (i.e., evaporator, condenser, etc.) when conditions are unfavorable. The types of faults that may cause protection concerns include electrical, mechanical, and system faults. Electrical faults typically have a direct effect on an electrical motor associated with the compressor, while mechanical faults generally include faulty bearings or broken parts. Mechanical faults often raise a temperature of working components within the compressor and, thus, may cause malfunction of and possible damage to the compressor.
In addition to electrical and mechanical faults associated with the compressor, the compressor and refrigeration system components may be affected by system faults attributed to system conditions such as an adverse level of fluids (i.e., refrigerant) disposed within the system or a blocked-flow condition external to the compressor. Such system conditions may raise an internal compressor temperature or pressure to high levels, thereby damaging the compressor and causing system inefficiencies and/or failures.
Conventional protection systems typically sense temperature and/or pressure parameters as discrete switches and interrupt power supplied to the electrical motor of the compressor should a predetermined temperature or pressure threshold be exceeded. While such sensors provide an accurate indication of pressure or temperature within the refrigeration system and/or compressor, such sensors must be placed at numerous locations within the system and/or compressor, thereby increasing the complexity and cost of the refrigeration system and compressor.
Even when multiple sensors are employed, such sensors do not account for variability in manufacturing of the compressor or refrigeration system components. Furthermore, placement of such sensors within the refrigeration system are susceptible to changes in the volume of refrigerant disposed within the refrigeration system (i.e., change of the refrigeration system). Because such sensors are susceptible to changes in the volume of refrigerant disposed within the refrigeration system, such temperature and pressure sensors do not provide an accurate indication of temperature or pressure of the refrigerant when the refrigeration system and compressor experience a severe undercharge condition (i.e., a low-refrigerant condition) or a severe overcharge condition (i.e., a high-refrigerant condition).